Question

I am doing a procedure and it’s working but I’m not sure if it’ll work in all cases as it’s not conventional.

void func (int &num){
    num=blah;
}

int main() {
    int num;
    func(num);
}

I know the conventional way of doing this is as below but still I have a lot of code in the previous format I prefer not to change as it works just fine. What I don’t understand is whether I’m just being lucky.

void func (int* num){
    *num=blah;
}

int main() {
    int num;
    func(&num);
}

In fact there is a bit more complicated version of it as well:

void func(float* &list){
    list=new float[3];
}

int main() {
    float *list;
    func(list);
}

which again I understand the conventional way of doing it is as below.

void func(float** list){
    *list=new float[3];
}

int main(){
    float *list;
    func(&list);
}

Your help is much appreciated as I’m in total confusion.

Answer 1

Your first example is correct – you’re passing an int by reference to func().

Your second example also fine (now that you’ve edited it). In this case, you’re passing an int * by value to func().

Your third and fourth examples are also both correct. In the third, you’re passing a float * by reference. In the second case, you’re passing a float ** by value (which is semantically similar to passing a float * by reference, which might be why you’re confusing them).

There’s nothing “conventional” or “unconventional” about any of your example code. All of it is 100% correct and will work fine. Though there are some subtle semantic differences between passing pointers by value and passing by references, these examples are ok.